1. Field of the Invention
The invention provides a method and composition for the removal of especially nonpolar stains from fabrics by using a mixture of densified carbon dioxide and a cleaning adjunct, which is a nonpolar liquid.
2. Brief Statement on Related Art
There has been limited recognition in the use of carbon dioxide to clean fabrics. Carbon dioxide has been used a standard propellant in the delivery of foaming cleaning products, e.g., Harris, U.S. Pat. No. 4,219,333.
Maffei, U.S. Pat. No. 4,012,194, described a dry cleaning system in which chilled liquid carbon dioxide is used to extract soils adhered to garments. The liquid carbon dioxide is converted to gaseous carbon dioxide, the soils removed in an evaporator and the gaseous carbon dioxide is then recycled. Maffei, however, does not teach, disclose or suggest the use of additional cleaning adjuncts in connection with his chilled liquid carbon dioxide dry cleaning system.
More recently, the use of supercritical fluids, e.g., carbon dioxide whose temperature has been elevated to past a so-called critical point, has been studied for the purposes of solvent extraction, as in, e.gs., Kirk-Othmer, Encycl of Chem. Tech., 3d Ed., Vol. 24 (Supplement), pp. 872-893 (1983) and Brogle, "CO.sub.2 in Solvent Extraction," Chem. and Ind., pp. 385-390 (1982). This technology is of high interest because of the need for little or no organic solvents in such extraction processes, which is very desirable from an environmental standpoint.
However, none of the prior art discloses, teaches or suggests the combination of densified carbon dioxide and a cleaning adjunct as a cleaning agent for the removal of soils and stains from fabrics, said cleaning adjunct being a nonpolar liquid. Nor does the art teach, disclose or suggest the use of such combination of densified carbon dioxide and a cleaning adjunct as a cleaning agent as a dry cleaning process, the novel combination providing an environmentally safe alternative to the use of ordinary dry cleaning materials such as Stoddard solvent or perchloroethylene ("perc").